Using scalable codecs for providing channel zapping information to broadcast receivers

ABSTRACT

Scalable codecs are used for transmitting channel zapping data for one or more programs using timeslicing. The main codec layer may be utilized also for the zapping data, and the higher layers may be used in the primary channels. Zapping data may be provided to mobile terminals via a wireless multicast network, such as a DVB-H network, using timeslicing and providing the scalably encoded zapping data as part of the source stream.

FIELD OF THE INVENTION

Aspects of the invention relate generally to mobile telecommunicationsnetworks. More specifically, aspects of the invention are directed tousing scalable codecs for providing channel zapping information tobroadcast receivers to allow fast channel switching.

BACKGROUND OF THE INVENTION

In conventional television broadcasting, whether programs are sentanalog or digital, a user may quickly and easily change channels inorder to see what programs are transmitted on each channel, e.g., oftenreferred to as zapping or channel surfing. In DVB-H (Digital VideoBroadcasting—Handheld) the programs are sent using timesliced IPDC(Internet Protocol Datacasting). The data of each program is sent inbursts usually using the entire or almost entire available bandwidth.The receiver portion of the DVB-H terminal is turned on only when theburst carrying the chosen program is transmitted. Between the bursts thereceiver is turned off and the received (buffered) burst is rendered.Powering down between bursts saves considerable amounts of power inmobile devices with limited battery life. If the user wants to viewanother program broadcast, he or she has to wait until the burstcarrying the desired program is transmitted. Because the time betweenbursts for each channel can be from a couple seconds up to 40 seconds ormore, fast channel switching is not possible. Thus, it would be anadvancement in the art to provide a method and system whereby userscould easily and quickly change channels in a bursting broadcastenvironment.

BRIEF SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order toprovide a basic understanding of some aspects of the invention. Thissummary is not an extensive overview of the invention. It is notintended to identify key or critical elements of the invention or todelineate the scope of the invention. The following summary merelypresents some concepts of the invention in a simplified form as aprelude to the more detailed description provided below.

To overcome limitations in the prior art described above, and toovercome other limitations that will be apparent upon reading andunderstanding the present specification, the present invention isdirected to methods and systems for providing zapping data for one ormore programs transmitted using timeslicing. Scalable codecs are usedfor transmitting channel zapping data for one or more programs usingtimeslicing. The main codec layer may be utilized also for the zappingdata, and the higher layers may be used in the primary channels. Zappingdata may be provided to mobile terminals via a wireless multicastnetwork, such as a DVB-H network, using timeslicing and providing thescalably encoded zapping data as part of the source stream.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features, and wherein:

FIGS. 1 and 2 show bit streams and resulting bit rates for non-scalableand scalable coding respectively.

FIG. 3 illustrates channels in a wireless broadcasting network.

FIG. 4 illustrates data in a time slice sequence according to anillustrative aspect of the invention.

FIG. 5 shows channel zapping information sent in separate bursts duringoriginal bursts in accordance with an aspect of the invention.

FIG. 6 is similar to FIG. 5 and shows the channel zapping data in moredetail than FIG. 5 does.

FIG. 7 illustrates selection of I-frames for use in a zapping streamaccording to an illustrative aspect of the invention.

FIG. 8 illustrates a method for providing zap data in a time slicedwireless broadcasting network according to an illustrative aspect of theinvention.

FIG. 9 illustrates a method for providing zapping information in amobile terminal.

FIG. 10 illustrates a method for providing zapping data according to anillustrative aspect of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description of the various embodiments, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration various embodiments in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural and functional modificationsmay be made without departing from the scope of the present invention.

Multimedia broadcasting is becoming a popular use case in varioussystems, including, but not limited to, IP datacasting (IPDC) overDVB-H. Mobile DTV (MDTV) is a North American version of IPDC, andcompetitors to them are Korean digital multimedia broadcasting (DMB) andQualcomm's MediaFlo.

IPDC sends data in bursts and each burst contains one or few services,as mapped by the service provider. As mentioned above, when a userchanges to the next service (also referred to as a “radio channel,”“radio station,” or “primary channel”), then that may be referred to as“channel browsing” or as “channel zapping”. The time interval betweentwo successive data bursts depends on the used bit rate, but should notbe more than about six seconds. It is typically approximately 1-2seconds. When services are in the same burst, then a terminal user canswitch quickly to the next service. But, if different services are indifferent data bursts, then there may be a delay of between zero and sixseconds, depending on when the next burst is available. That switchingtime can be reduced so that before the next burst is available, a lowerbit rate version of the same content is rendered. Such content is sentin dedicated zapping channels. In IPDC, the support of zapping channelis optional. FIGS. 1-4 show various ways to include separate zappingchannels. For example, zapping channels could be transmitted afterElectronic Service Guide (ESG) data, with ESG-data, time-wise parallelto services, or after each service.

Zapping support can be provided to the user with two options from theElectronic Service Guide ESG point of view: (1) dynamic zapping, wherethe zapping support is provided, not as part of the Electronic ServiceGuide (ESG) data, so it can be dynamically changing; and (2) staticzapping, where the zapping Support is provided in the ESG.

A dynamic zapping service is a streaming service on a separate (InternetProtocol) IP flow in a separate zapping burst. Such a service containscomplementary content about the associated main streaming service. Whenthe zapping content is synchronized with the main stream then thezapping content is updated continuously, i.e., dynamically. Such zappingcontent could be, for example, a copy of the audio/video content withreduced performance, a still picture showing the latest snapshot out ofthe current video or dynamic text such as subtitles. Also, a combinationof the aforementioned is possible.

On the other hand, static zapping content is provided in ESG auxillararydata. Static zapping content tries to give an impression of the mainaudio/visual (A/V) streams by graphics or simple text. Thus, staticzapping content data is not updated or synchronized with the mainstreaming service, but is transported significantly in advance relativeto the streaming content service.

In “traditional” non-scalable coding for various desired quality levels,or available bit rates, separate bitstreams are encoded and saved at theserver side. Then, a server sends each such bit stream separately, and adecoding client device decodes the separate bit streams. In somestreaming applications, bit streams could be changed during service whenusing extra negotiations. Moving Picture Experts Group (MPEG) hasspecified its MPEG-4 Advanced Audio Coding—Low Complexity (AAC LC) thatis an example of such an audio codec.

With scalable coding, low resolution data is encoded into a core streamlayer (also referred to as a base stream layer) and higher resolutiondata is achieved by using one or more separate enhancement layers withthat core stream layer. A core stream typically contains a full roughrepresentation of the information to be transmitted, i.e., the resultingquality is acceptable as a low bit rate version but some encodingartifacts are audible or often also audio bandwidth could be limited.

In certain embodiments, the enhancement layers include information thatimproves the quality of the core stream layer, for example by increasingthe audio or video bandwidth, or adding more image detail and reducingcoding artifacts that are caused by lossy coding algorithms. Typically,an enhancement layer alone cannot be converted into a representation ofusable information, it has to be used together with the core streamlayer. An enhancement layer may have a lower bit rate than the corestream layer, or it may have a higher bit rate than the core streamlayer. By defining the bit rates for the core stream layer and the oneor more enhancement layers and the relation between their respective bitrates, the quality and the quality relation of the information coded inthe core stream layer and the core stream layer when decoded with one ormore enhancement layers can be defined.

By using a core stream layer and one or more enhancement layers, at theserver side, a single copy of the content (i.e., the core stream and theassociated enhancement layers) may be saved. The resulting total bitrate of such files is the sum of the bit rate of the base layer and thebit rates of the enhancement layers. MPEG-4 AAC Scalable and MPEG-4Bit-Slice Arithmetic Coding (BSAC) are examples of scalable audiocodecs. They may run over normal non-scalable codecs, and, therefore,the base layer could be at the lowest level even 10 to 20 kbps.

When a server is sending a scalable bit stream, then the used layers canbe selected according to an available bit rate and/or a desired quality.In practise, that would be a “cumulative combination” of the core streamand a selected amount of layers. If streaming of content is notexpensive, then a server may send the full stream, and then it is up tothe decoding client devices to select which layers they are decoding andwhich layers they will simply ignore. That selection could be alsochanged in real-time, e.g., due to changes in the network condition.Because the core stream is the most important part of the bit stream, itcould have the highest priority in transmission, or it could get moreforward error correction, etc. For example, when there is networkcongestion, then an advanced network device would be able to drop thelower priority enhancement layers in order to enable transmission of thehigher priority core streams.

FIGS. 1 and 2 show bit streams and resulting bit rates for non-scalableand scalable coding respectively. The resulting total bit rate increasesas a function of N.

In wireless streaming, the bit rate per stream should be as low aspossible due to transmission costs, power consumption of the receiver,and similar considerations. Thus, even if the layered scalability canresult in the overall bit rate reduction in the case when many layersare streamed together, then the situation is different when it iscompared to the case when streams are streamed separately because in thelatter case the total bit rate per stream per encoded content item isless than in the former case. Therefore, for wireless multimediastreaming standards like Third Generation Partnership (3GPP) MultimediaBroadcast/Multicast Service (MBMS) and Packet-switched Streaming Service(PSS), non-scalable codecs have been selected to achieve an optimalperformance per stream. The current Release-6 (and soon finalizedRelease-7) versions of those standards use H.263, MPEG-4 Part 2 orMPEG-4 Part 10 (aka AVC/H.264) for PSS for several reasons. For newerMBMS service AVC is used. For audio services both AdaptiveMulti-Rate—Wideband (AMR-WB+) and High Efficiency AAC v2 (HE AAC v2)decoding can be implemented.

When codecs for IPDC over DVB-H were selected, the harmonization ofcomponents between 3GPP and IDPC was one target because it can beexpected that many mobile device would support both those standards.Therefore, the codec lists of IPDC and 3GPP are very similar; in IPDCfor video AVC/H.264 is used again, and for audio HE AAC v2 and AMR-WB+.In IPDC service, however, Video Code 1 (VC-1) may be used, but not thoseolder H.263 and MPEG-4 Part 2. IPDC applications are divided into a fewcapability classes according to the used video and audio codingparameters.

When an optional IPDC zapping service is used, then each zapping streamis sent separately, in addition to the used main channel.

Even if relatively high resolution zapping channels are desired, asignificant issue with their usage is that they either consume part ofan overall bit budget or they increase the total bit rate. In the formercase, the quality of primary channels is reduced, and a good trade-offshould be found (e.g., balancing the audio/video quality for mostly usedprimary channel versus the audio/video quality for channels that areused for channel zapping (i.e., new channel selection)). If the totalbit rate is increased due to usage of the zapping channels, then itresults in increased power consumption.

When a user is listening to a single radio program for a relatively longtime and is not using channel zapping, then sending channel zapping datain a parallel channel is an unnecessary overhead.

Also, supporting channel zapping increases the complexity in thereceiver side because the receiver decodes two or more separate streams(e.g., the primary channels and the lower bit rate zapping channel thatmight use different encoding tools etc).

Zapping content is not yet used much, but content streams for primarychannels and zapping channels are encoded and sent separately. Thus,even if optimal bit rates were used for both the primary channels andthe zapping channels, then the overall bit rate would no longer beoptimal. And supporting separate zapping channels increases thecomplexity of the system. This is because such a system handles multiplestreams, initializes codecs for the streams in the beginning of theservice, and the sender side also encodes the zapping content andsynchronizes the zapping content with the corresponding primarychannels.

In accordance with various aspects of the invention, instead of sendingseparate better quality primary channels and lower bit rate zappingdata, scalable codecs are used for sending both the primary channels andthe zapping data. The main codec layer is the core stream layer and maybe used for the zapping data, and the higher layers (also referred to asenhancement layers) may be used in the primary channels. In this way,the overhead associated with a separate zapping channel that duplicatescontent from an associated content service is avoided. In that way thereceiver may process the same kind of bitstreams; either the core streamor both the core and one or more associated enhancement layers.

FIG. 3 illustrates physical channels (e.g., radio channels) f1, f2, f3and fn in a frequency band used, e.g., for DVB transmissions. In theexample frequency band, channel f1 may be used for timesliced IPdatacasting (IPDC) transmissions. On frequency f1 a number of IPservices, or programs, may be sent. Programs may be grouped into logicalchannels A1, B1, C1 each comprising one or more services, or programs.Additionally, Electronic Service Guide (ESG) data, Service Information(SI) data, and Program Specific Information (PSI) data may betransmitted on the same physical channel f1. As used herein, either theterm service or program may be used to refer collectively to servicesand programs. Other frequencies may carry other programs or services.E.g. a DVB-T service may be sent on f2. On frequency fn, services An,Bn, Cn, ESGn, Sin, and PSIn may be sent, as illustrated in FIG. 3.

FIG. 4 illustrates timesliced transmissions on a sample frequency, heref1, in a simplified example. Each logical channel A1, B1 and C1comprises one or more IP services, or programs. Data corresponding toone or more IP services of the logical channel may be transmitted as asingle burst using all or most of the available bandwidth of thephysical channel during that time slot. The logical channel may also bethought of or referred to as a timesliced channel. For receiving an IPservice in a timesliced channel, e.g., A1, the receiver is turned on forthe duration 201 of the burst carrying channel A1 data. The maximumburst duration is signaled in SI data 203. A time to next burst(delta-t), the end of the burst/frame, and any application data tableand/or RS data table may be signaled as real-time parameters in thetransmitted MPE section headers (not shown). A receiver receiving thetransmission may filter the corresponding packets from the receivedburst in order to receive a selected program in the channel. In theexample of FIG. 4, A1, B1, and C1 are timesliced elementary streams(timesliced channels) each comprising one or more IP services. AnElectronic Service Guide (ESG) comprising information on the hierarchyand/or content of the services, transmission times and other servicerelated information associated with the available services or programsof the timesliced channels A1, B1, and C1 may be transmitted as aseparate burst, as illustrated in FIG. 4.

Because data in the ESG might not be descriptive enough for a userregarding the content of a program, or because the user wants to see atwhat point a program is presently being broadcast, the user decides toswitch channels in rapid succession to learn what is being broadcast inother ongoing programs. This is also known as channel zapping. However,because the time between bursts for each channel can be up to 40 secondsor more, an illustrative aspect of the invention may provide zappingdata to the receiver. The user can then review the zapping data whendesiring to rapidly see what is being broadcast on other channels. Thezapping data may be consumed in the receiver by a client zappingapplication. The zapping data may present to the user a view of ongoingprograms being broadcast on a number of available channels.

As mentioned above, in accordance with an illustrative aspect of theinvention, scalable codecs may be used for sending both the primarychannels and the zapping data. The main codec layer may be used also forthe zapping data, and the higher layers (also referred to as enhancementlayers) may be used in the primary channels.

FIG. 5 shows channel zapping information sent in separate bursts duringoriginal bursts, which may be referred to as bit-rate interleaving, inaccordance with an aspect of the invention. FIG. 5 illustrates timesliced zapping content transmission, where zapping bursts are sent inparallel with content services. Small zapping bursts, each of whichcontains content from a single service burst, are provided.

While in a normal mode, receivers receive the time sliced channel A(including, for example, programs 1, 2, 3, 4)+“zapping” time slicechannel Azap (including zapping frames for programs 1, 2, 3, 4). In azapping mode, the receiver may receive all zapping channels

Az . . . Nz, including zapping frames from all programs. Receivers arepreferably capable of receiving substantially all the zapping program inzapping mode.

Advantages of this method of providing channel zapping informationinclude that no extra capacity is required from the air interface ascontent for zapping is only logically separated from original content,and MPE-FEC interleaving depth is the same as original burstinterleaving depth. However, receiver filtering and buffering becomesmore complicated as both “real” and “zapping” time slice channels needto be received. In addition, in zapping mode, the receiver needs to be“on” all the time, and zapping content modifications are not possible atthe transmitter side as zapping content is also content for actualservice. However, modifications to the zapping information may becarried in the ESG. For example, text transmitted in the ESG may beoverlayed on a displayed zapping channel.

FIG. 6 is similar to FIG. 5 and shows the channel zapping data in moredetail than FIG. 5 does. As shown in FIG. 6, channel zapping data forservice A, includes a core (also referred to as main or primary) channelzapping data and enhancement layers (A1-A4) of additional channelzapping data for channel A. The core channel zapping data provides lowresolution information, and each enhancement layer adds higherresolution channel zapping information. The core zapping layer and theenhancement layers are each decodable by a scalable decoder inaccordance with various aspects of the invention. As shown in FIG. 6,services B and C also comprise a core layer of channel zappinginformation and enhancement layers of channel zapping information.

The core layers (Core_A, Core_B, and Core_C) may use different amountsof bandwidth, as shown in FIG. 6 by the different heights of the corelayers Core_A, Core_B, and Core_C. Similarly, the enhancement layers mayuse different amounts of bandwidth, as shown in FIG. 6 by the variationsin the respective heights of the enhancement layers EL_A1-A4, EL_B1-B4,and EL C1-C3. Channel C is shown having 3 enhancement layers, whilechannels A and B each have 4 enhancement layers. Other suitable numbersof enhancement layers may also be used. Different enhancement layers maybe used for different aspects. For example, one layer may be used forimage resolution; another layer may be used for a higher frame rate, andthe like.

As is known in the art, scalable codecs can be decoded at differentrates. At a low data rate, with low computational effort, they may bedecoded to get a low resolution image, video, or audio. At a higher datarate, with higher computation effort, decoding will yield a higherresolution image, video, or audio. In accordance with various aspects ofthe invention, for channel zapping, core channel zapping information maybe decoded at a relatively low data rate. In this way, fast switchingbetween content channels is facilitated. In addition, computationaleffort for decoding several zapping channels is kept under control, sothat devices with low computational capabilities can decode a highnumber of zapping channels. When not in channel zapping mode, the corechannel zapping information and one or more enhancement layers may bedecoded to render higher quality content to a terminal user.

As indicated in “Scalable Codec Architectures for InternetVideo-on-Demand”, Girod et al, Telecommunications Laboratory Universityof Erlangen-Nuremberg, Cauerst. 7, 91058 Erlangen, Germany, which isincorporated herein by reference, scalable video coding may be based ona spatio-temporal resolution pyramid. The scalable codec exploitsspatio-temporal redundancies of the pyramid decomposition by anefficient compression technique. Low complexity downsampling andinterpolation filters are combined with highly efficient lattice vectorquantization. For intra coded picture frames (I-frames, that represent afixed/frozen image and serve as an anchor in motion image coding), theoriginal frame is successively filtered, and downsampled by a simpleaveraging filter with coefficients (11), separately applied inhorizontal and vertical direction. The lowest resolution layer isencoded by a DPCM (differential pulse code modulation) technique. Forall other layers, a spatial prediction is formed by interpolating thelower resolution layer by a filter with coefficients (1 3 3 1) againapplied horizontally and vertically. Spatially predicted frames can beused for any other type of lower resolution frames. The residualprediction error quantizer may use an 8-dimensional lattice vectorquantizer (LTVQ). For encoding, a 2×4 block of neighboring samples maybe mapped into an 8-dimensional vector. This vector may be scaled by afactor of 1/s, s>>1 where s corresponds to the quantizer step size inone-dimensional quantization. By varying s, the bit-rate of thequantizer can be controlled. The scaled vector, a point in R⁸, isrounded to its nearest E₈-lattice point. From the obtained latticepoint, an index is computed which then is transmitted to the decoder.The decoder can reconstruct the lattice point from the received indexeither by computation or by a simple table-lookup. By resealing thereconstructed lattice point with s, the finally constructed 2×4 inputblock is obtained.

According to an aspect of the invention, I-frames may be used inconjunction with zapping data for video programs. I-frames may beidentified from the broadcast stream, e.g., in MPEG-2 the Group ofPictures layer (GOP) data may be used. With reference to FIG. 7, thestreams S1, S2 and S3 represent program streams (IP services) that maybe transmitted in one timesliced channel, e.g., channel A. In theexample in FIG. 7, streams S1, S2 and S3 are video streams comprisingI-frames and inter-coded frames (p- and b-frames—for simplicity both p-and b-frames are shown with ‘p’). The size of the (video) frame candiffer from frame to frame. The program streams may include, in additionto the video data, other data such as, e.g., audio data, text dataand/or image data that is part of the program or relating to theprogram. The program streams may also include data not related to theprogram (e.g. advertisements). In the example of FIG. 7, the zappingdata is formed from I-frames of each program stream S1, S2, and S3. Thezapping data may also include other data selected from each programstream S1, S2, and S3, if desired. The zapping data is preferablyselected so that it is representative of the program carried in thecorresponding program stream(s).

All or some of the I-frames of each stream may be selected to beincluded in the zapping data. The selection can be different fromprogram to program, or consistent across streams and/or programs. InFIG. 7, lines S1 z, S2 z, and S3 z represent zapping data selected fromstreams S1, S2, and S3. In the example of FIG. 7, the I-frames selectedto be included in the zapping streams are illustrated with solid bordersin streams S1 z, S2 z, and S3 z, i.e., IA-1, IA-2, IA-3, IB-1, IB-3,IC1, and IC-4.

An illustrative aspect of the invention provides a mechanism forswitching from zapping mode (i.e., fast channel switching to learnprogram content) to a real-time viewing mode of a selected program,using the electronic service guide (ESG), as further described below. Ifand when the user wants to return to a program from which he/she changedto zapping mode, the receiver may be turned on for receiving real-timeparameters on that current channel or program. The receiver needs toreceive only one (correct) section to get the delta-t for the desiredcontent, and can then be turned off using power control mechanisms. Thereceiver can thus keep track of the real-time parameters for returningto the original program.

The receiver can tune to a desired program by accessing the ESG data. Asshown in FIG. 8, the receiver may be turned on during one or moretimeslice bursts, as in R1. If the receiver is turned on for theduration of all bursts, as in R2, the receiver can be ‘tuned’ to anyprogram carried in the bursts. If the receiver is turned on for theduration of one burst, the programs carried in that burst can beaccessed directly. Az, Bz, and Cz represent zapping data correspondingto channels A, B and C, respectively.

FIG. 9 illustrates a method for providing zapping data to auser/terminal in accordance with an aspect of the invention. Forexample, if the user takes an action and triggers a channel change, theterminal may request the receiver to filter out zapping datacorresponding to the channel that the user tuned in. This data may berendered to the user as soon as the filtering is done. Once theadditional enhancement layer data is available, which may already be thecase or which may be the case after another data burst is received, theterminal may render the higher quality content for the user.

An example of receiver operation in an illustrative DVB-H embodiment isdescribed with respect to FIG. 10. FIG. 10 illustrates a method forpresenting zapping data and tuning to a desired program. A mobileterminal (not shown) in step 1001 receives PSI/SI signaling that mapsIP(A), IP(B), IP(ZA), IP(ZB) and IP(ESG) to DVB-H link parameters suchas PID. The mobile terminal listens in step 1003 for an IP(ESG) address(which in turn causes DVB-H tuning, filter creating, etc.) and in step1005 starts receiving ESG objects over address IP(ESG). For eachreceived ESG entry the mobile terminal starts receiving a zapping streamin step 1007. That is, the mobile terminal starts listening for IP(ZA),IP(ZB). In step, 1008, a terminal user consumes content in zappingquality, and processing continues at step 1013. In step 1009 a datagramarrives at address IP(ZA), the datagram being an I-frame containingzapping image data for service A. The mobile terminal knows the datagramhas an I-frame because the binding is available in ESG entry 1. The sameapplies for other addresses IP(ZB), IP(ZC), etc. In step 1011 thereceived datagram is stored in mobile terminal data storage associatedwith ESG entry. If there is already a datagram, it is simplyoverwritten. This way the zapping stream updates zapping pictures forall services for which the mobile terminal has entries. In step 1013, auser browses the ESG structure going through ESG entries that are storedin terminal data storage. Browsing quickly (zapping) the entries, theterminal quickly renders the stored zapping image related to the entry(received in 1009 and stored in 1011). If the user stops browsing for Tseconds at a particular entry (step 1015), the mobile terminal in step1017 automatically tunes to the selected service D, and starts bufferingand playing back the data stream from address IP(D). While buffering andstarting, the terminal renders the last zapping image that was receivedthrough IP(DZ).

One or more aspects of the invention may be embodied incomputer-executable instructions, such as in one or more programmodules, executed by one or more computers or other devices. Generally,program modules include routines, programs, objects, components, datastructures, etc. that perform particular tasks or implement particularabstract data types when executed by a processor in a computer or otherdevice. The computer executable instructions may be stored on a computerreadable medium such as a hard disk, optical disk, removable storagemedia, solid state memory, RAM, etc. As will be appreciated by one ofskill in the art, the functionality of the program modules may becombined or distributed as desired in various embodiments. In addition,the functionality may be embodied in whole or in part in firmware orhardware equivalents such as integrated circuits, field programmablegate arrays (FPGA), and the like.

The present invention includes any novel feature or combination offeatures disclosed herein either explicitly or any generalizationthereof. Any of the method steps disclosed herein can be implemented incomputer software, hardware, or combinations thereof, and may beembodied on computer-readable media. Functions for selecting, forming,transmitting, receiving, processing, and displaying can be carried outusing one or more processors and/or other chipsets programmed to carryout the respective functions. While the invention has been describedwith respect to specific examples including presently preferred modes ofcarrying out the invention, those skilled in the art will appreciatethat there are numerous variations and permutations of the abovedescribed systems and techniques. Thus, the spirit and scope of theinvention should be construed broadly as set forth in the appendedclaims.

1. A method comprising: scalably encoding a core stream of data for adigital broadcast service; scalably encoding at least one enhancementlayer of data for the digital broadcast service; and broadcasttransmitting, in a common timeslice for the time-sliced digitalbroadcast service, the scalably encoded core stream of data and thescalably encoded at least one enhancement layer of data.
 2. The methodof claim 1, wherein the core stream of data includes channel zappingcontent that comprises a low resolution version of the time-sliceddigital broadcast service.
 3. (canceled)
 4. The method of claim 1,wherein the scalably encoding steps are performed based on aspatio-temporal resolution pyramid and wherein the scalably encodingsteps further combine downsampling and interpolation filters withlattice vector quantization. 5-7. (canceled)
 8. A method comprising:receiving a scalably encoded core stream of data and at least onescalably encoded enhancement layer of data; decoding the scalablyencoded core stream of data; and rendering as channel zapping contentthe decoded core stream of data.
 9. The method of claim 8, wherein thescalably encoded core stream of data and the at least one scalablyencoded enhancement layer of data are received in a common timeslice fora time-sliced digital broadcast service.
 10. The method of claim 8,further comprising: decoding the at least one scalably encodedenhancement layer of data and rendering the decoded core stream of dataand the decoded enhancement layers of data as a primary content service.11. The method of claim 8, further comprising: decoding all or fewerthan all of the at least one scalably encoded enhancement layers of dataand rendering the decoded core stream of data and fewer than all of thedecoded enhancement layers of data as channel zapping content.
 12. Themethod of claim 8, wherein the primary content service is rendered inresponse to user input selecting the primary content service forconsumption.
 13. The method of claim 8, wherein the primary contentservice includes video content.
 14. The method of claim 8, wherein theprimary content service include audio content.
 15. An apparatus having acomputer readable medium that contains computer executable instructionsfor causing the apparatus to perform operations comprising: scalablyencoding a core stream of data for a digital broadcast service; scalablyencoding at least one enhancement layer of data for the digitalbroadcast service; and broadcast transmitting, in a common timeslice forthe time-sliced digital broadcast service, the scalably encoded corestream of data and the scalably encoded at least one enhancement layerof data.
 16. The apparatus of claim 15, wherein the core stream of dataincludes channel zapping content that comprises a low resolution versionof the time-sliced digital broadcast service.
 17. (canceled)
 18. Theapparatus of claim 15, wherein the scalably encoding steps are performedbased on a spatio-temporal resolution pyramid and wherein the scalablyencoding steps further combine downsampling and interpolation filterswith lattice vector quantization. 19-21. (canceled)
 22. An apparatushaving a computer readable medium that contains computer executableinstructions for causing the apparatus to perform operations comprising:receiving a scalably encoded core stream of data and at least onescalably encoded enhancement layer of data; decoding the scalablyencoded core stream of data; and rendering as channel zapping contentthe decoded core stream of data.
 23. The apparatus of claim 22, whereinthe scalably encoded core stream of data and the at least one scalablyencoded enhancement layer of data are received in a common timeslice fora time-sliced digital broadcast service.
 24. The apparatus of claim 22,further comprising: decoding the at least one scalably encodedenhancement layers of data and rendering the decoded core stream of dataand the decoded enhancement layers of data as a primary content service.25. The apparatus of claim 22, further comprising: decoding all or fewerthan all of the at least one scalably encoded enhancement layers of dataand rendering the decoded core stream of data and fewer than all of thedecoded enhancement layers of data as channel zapping content.
 26. Theapparatus of claim 22, wherein the primary content service is renderedin response to user input selecting the primary content service forconsumption.
 27. The apparatus of claim 22, wherein the primary contentservice includes video content.
 28. The apparatus of claim 22, whereinthe primary content service include audio content. 29-30. (canceled)